Electrical stimulation can be useful for treating a variety of conditions. Deep brain stimulation can be useful for treating, for example, Parkinson's disease, dystonia, essential tremor, chronic pain, Huntington's Disease, levodopa-induced dyskinesias and rigidity, bradykinesia, epilepsy and seizures, eating disorders, and mood disorders. Typically, a lead with a stimulating electrode at or near a tip of the lead provides the stimulation to target neurons in the brain. Magnetic resonance imaging (“MRI”) or computerized tomography (“CT”) scans can provide a starting point for determining where the stimulating electrode should be positioned to provide the desired stimulus to the target neurons.
After the lead is implanted into a patient's brain, electrical stimulus current can be delivered through selected electrodes on the lead to stimulate target neurons in the brain. Typically, the electrodes are formed into rings disposed on a distal portion of the lead. The stimulus current projects from the ring electrodes equally in every direction. Because of the ring shape of these electrodes, the stimulus current cannot be directed to one or more specific positions around the ring electrode (e.g., on one or more sides, or points, around the lead). Consequently, undirected stimulation may result in unwanted stimulation of neighboring neural tissue, potentially resulting in undesired side effects.
One embodiment is an implantable electrical stimulation lead including a lead body having a distal portion, a distal tip, and a proximal portion; a plurality of electrodes disposed along the distal portion of the lead body; a plurality of terminals disposed along the proximal portion of the lead; and a plurality of conductors, each conductor electrically coupling at least one of the electrodes to at least one of the terminals. The plurality of electrodes includes a tip electrode disposed on the distal tip of the lead body. The tip electrode has a base and a separate plug attached to the base. The base defines an interior lumen closed at one end by the plug. A portion of the lead body extends into the interior lumen of the base.
Another embodiment is an implantable electrical stimulation lead including a lead body having a distal portion, a distal tip, and a proximal portion; a plurality of electrodes disposed along the distal portion of the lead body; a plurality of terminals disposed along the proximal portion of the lead; and a plurality of conductors, each conductor electrically coupling at least one of the electrodes to at least one of the terminals. The plurality of electrodes includes a tip electrode disposed on the distal tip of the lead body. The tip electrode has an electrode body, a stem extending from the electrode body, and a plurality of shaped retention features extending from the stem. A portion of the lead body extends around the stem and shaped retention features. The shaped retention features facilitate retention of the tip electrode on the lead body.
Yet another embodiment is an implantable electrical stimulation lead including a lead body having a distal portion, a distal tip, and a proximal portion; a plurality of electrodes disposed along the distal portion of the lead body; a plurality of terminals disposed along the proximal portion of the lead; and a plurality of conductors, each conductor electrically coupling at least one of the electrodes to at least one of the terminals. The plurality of electrodes includes a tip electrode disposed on the distal tip of the lead body. The tip electrode has an electrode body, a stem extending from the electrode body, and a flange attached to the stem opposite the electrode body. A portion of the lead body extends around the stem and flange. The flange facilitates retention of the tip electrode on the lead body.
A further embodiment is an implantable electrical stimulation lead including a lead body having a distal portion, a distal tip, and a proximal portion; a plurality of electrodes disposed along the distal portion of the lead body; a plurality of terminals disposed along the proximal portion of the lead; and a plurality of conductors, each conductor electrically coupling at least one of the electrodes to at least one of the terminals. The plurality of electrodes includes a tip electrode disposed on the distal tip of the lead body. The tip electrode has an electrode body and the electrode body defines an interior lumen and a plurality of protrusions extending into the interior lumen. A portion of the lead body extends into the interior lumen of the electrode body. The plurality of protrusions in the interior lumen facilitates retention of the tip electrode on the lead body and hinders rotation of the tip electrode around the distal tip of the lead body.
Another embodiment is an implantable electrical stimulation lead including a lead body comprising a distal portion, a distal tip, and a proximal portion; a plurality of electrodes disposed along the distal portion of the lead body; a plurality of terminals disposed along the proximal portion of the lead; and a plurality of conductors, each conductor electrically coupling at least one of the electrodes to at least one of the terminals. The plurality of electrodes includes a tip electrode disposed on the distal tip of the lead body. The tip electrode has an electrode body and a plurality of arms extending from the electrode body. The electrode body defines an interior lumen and an opening to the interior lumen. The plurality of arms extends over the opening to the interior lumen. A portion of the lead body extends into the interior lumen of the electrode body and around the plurality of arms. The plurality of arms facilitates retention of the tip electrode on the lead body.